A test system for electronic device testing can include a pin driver circuit that provides a voltage test pulse to a device under test (DUT). In response, the test system can be configured to measure a response from a DUT, such as to determine whether the DUT meets one or more specified operating parameters. A test system can optionally include multiple driver circuits, such as a class AB driver circuit and a class A driver circuit to provide circuit test signals having different amplitude or timing characteristics. In an example, the test system is configured to measure a response from a DUT using an active load and a comparator circuit to sense transitions at a DUT pin.
Various comparator circuit structures have been proposed. Some have enhanced latching accuracy or enhanced bandwidth capabilities for operations such as high-speed sampling in applications such as analog-to-digital converters or automatic test equipment. In an example, a comparator circuit includes an AC input node, a DC input node, and an output node. In an example that includes a comparator in a circuit configured to execute automated testing of a DUT, the AC input node can be coupled to a DUT interface node, and the DC input node can be coupled to a reference voltage signal. Signal changes at the output node of the comparator circuit can indicate a relationship between the DUT output and the reference voltage signal.
Automatic test equipment can be qualified to perform various tests according to, among other things, propagation delay characteristics associated with a comparator circuit in the ATE. A propagation delay characteristic of the comparator circuit can depend in part on characteristics of the signals received from the DUT via the DUT interface node. For example, changes in any one or more of the slew rate, rise time, overdrive status, polarity, or duty cycle at the AC input node can influence a propagation delay characteristic of the comparator circuit.